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WHY THE HYPE?
wire, polymer filament, powders, liquids, gels, mixtures of glues
and materials, and slurries. ASTM International (previously the
American Society for Testing and Materials) notes seven primary
manufacturing processes. Within those exists a growing list of
more specialized methods. It is entirely possible that more have
been developed since ASTM’s survey of the state of the art. That’s
how fast the technology moves.
QUICK AND CUSTOM
Quick custom design and build is one of the great promises of
additive manufacturing as a category. In theory, every pair of
shoes that every Soldier wears could be custom fit and printed to
match the contours of a Soldier’s feet. Indeed, at least one major
athletic shoe brand makes a shoe that’s entirely additively manu-
factured, although it’s not customized to each pair of feet. Yet.
That customization possibility extends to both very large objects,
such as the buildings that the U.S . Army Corps of Engineers’
Automated Construction of Expeditionary Structures program
is making, to the extremely small, such as the 4D robots (the
fourth dimension is motion) that the Institute for Soldier Nano-
technologies at the Massachusetts Institute of Technology (MIT)
recently developed. Dr. Xuanhe Zhao and his team created “soft,
magnetic, 3D-printed structures that can transform their shape
almost instantaneously by the wave of a m ag n et .”
That speed is the real breakthrough, Zhao said in an interview
with Army AL&T, but the use of nanomaterials is nothing to
sneeze at. Currently, he said, “the drawback of existing [4D] struc-
tures is that their movement [is] very sl o w.”
Zhao, an associate professor at MIT and a researcher at the Insti-
tute for Soldier Nanotechnologies, said, “What we developed is
basically a new material system for 3D printing.” In additive
manufacturing, conceptually, the process, the design and the
materials are all equally important. Zhao’s team’s new method
places nanomagnetic particles strategically within the soft plastic.
The placement and orientation of the materials enable controlled,
rapid movement. “We use a new stimulation method, which is
magnetic.” Watching video of the structures is a bit like watch-
ing muscles twitch.
Indeed, Zhao, said, that’s the point. “You can reach the level of
energy density and the power density of real muscles. So now, we
can make it move very fast and forceful.”
Zhao said the technology that he and his team invented has
real promise for biomedical devices that can be customized, but
neither the printer nor the ink for the method they used existed,
so they had to invent them. “We invented a printing method
and the ink so that ... researchers can print structures that they
want—different shapes of robots, different shapes of actuators—
and when we apply a magnetic field, you can actuate it or you
can move this object.”
Watching the structures move, it’s not hard to imagine why Zhao
said the team envisions them in medical applications. “We are
actually trying to simulate the functions of the heart, so the heart
beating, and muscle contraction inside the human body. And
also, we are making this kind of magnetic materials, 3D-printed
into, for example, catheters. But those catheters, you know, are
smart. ... They can steer themselves inside the human body. For
example, in the blood vessel, they can make turns. ... So that
indeed is one ... project we are working on.”
‘ADDITIVE DOESN’T CARE’
Human beings have been making things for thousands of years.
The word “manufacturing” actually means “handmade,” coming
from the Latin for hand (manu) and made (factum), despite
current connotations of machine-made.
Doing something for thousands of years means that an almost
intuitive understanding of the materials and processes has been
passed down from generation to generation. Sloughing off the
knowledge built from thousands of years of doing the same thing
and perfecting it evolutionarily is not an easy task, and that can be
a serious problem for designers—that and the addition of poten-
tially millions more variables into the manufacturing process.
“ We use four additive
manufacturing machines
there, which we run 24 hours
a day, and what we’re building
is going right into the hands
of U.S . Soldiers.”
92
Army AL&T Magazine
January-March 2019